Although there doesn't appear to be a way to enter the justification directly as an input to any existing vi, there is a way to modify a vi to get the desired alignment.
The vi I modified was the "Font Style.vi" located in the "Set Report Font.vi". I added another property node off of the NIReports.Report reference. I selected the alignment property, changed it to write and created a control. There is now a control on the front panel to allow you to choose from left/right/center. You could pass the choice from your top level vi by just adding the alignment input to the necessary subvi's.
I have attached the modified vi for your review.
Matt Kisler
Application Engineer
National Instruments
http://www.ni.com/ask